I tried 
\directlua{lxml.registerentity("DATE","NEWDATE")}
and
\directlua{lxml.registerentity("DATE","NEWDATE")}

but neither does effect a change in the entity.

Why is that entry not set in the Lua-table entities? (file xml-ent.lua) has as that function:

function xml.registerentity(key,value)
    entities[key] = value
    if trace_entities then
        report_xml("registering entity %a as %a",key,value)
    end
end


> On 17 Apr 2023, at 12:32, Hans van der Meer <havdmeer@ziggo.nl> wrote:
> 
> I would like to change an entity 'on the fly'. Example
> 
> \def\DATE{THEDATE}\expanded{\xmlsetentity{DATE}{\DATE}}
> 
> \startxmlsetups typ:event
> 
> 	\def\DATE{NEWDATE}\expanded{\xmlsetentity{DATE}{\DATE}}
> 
> Using &DATE; within the <event>.
> 
> \stopxmlsetups
> 
> However, using &DATE; inside an <event> always results in THEDATE and never in NEWDATE.
> 
> How can I change the value of the entity inside the xmlsetups?
> 

dr. Hans van der Meer